Wireless communication comprises communication that takes place using electromagnetic radiation, such as optical light or radio waves. Electromagnetic radiation may be encoded with information that it is desired to communicate from a transmitter to a receiver, such that the receiver may decode the information once it receives the electromagnetic radiation.
In wireless communication systems with multiple users, such as for example cellular communication systems, controlling interference is a design goal. Interference occurs when more than one transmitter transmits using a same frequency at the same time. Transmissions on different frequencies do not directly interfere with one another, which is a fundamental aspect of electromagnetic radiation.
Methods for controlling interference include time division multiple access, TDMA, where a radio resource, such as a frequency, is time spliced so that a plurality of terminals can use the radio resource, but only one may use it at any given time. To facilitate TDMA a radio resource may be spliced into frames and/or timeslots, for example.
Another method for controlling interference is frequency division multiple access, FDMA, where a radio resource, such as a frequency band, is spliced to a plurality of frequencies, such that terminals may each be given a frequency to use. Since terminals operate on disparate frequencies, no direct interference occurs between transmissions from such terminals.
Yet further methods for controlling interference include code division multiple access, CDMA, where spreading codes are used to share a same radio resource between a plurality of users, and orthogonal frequency division multiple access, ODFMA, where each user may be assigned a set of subcarriers. Interference mitigation methods may be combined, for example by combining elements of TDMA and CDMA.
Half duplex communication comprises two-way communication by arranging separate radio resources for the communication directions. For example, in a cellular communication system timeslots may be assigned for uplink communication, and separate timeslots may be assigned for downlink communication. Full duplex, on the other hand, involves simultaneous communication in both directions. In a cellular communication example, it may involve simultaneous communication in two directions using the same radio resources.